class AttrHold(object):
   pass

ne = AttrHold()
ne.one = 1
ne.two = None
ne.three = 3
ne.four = 4
ne.six = 6
ne.seven = 7

ld = AttrHold()
ld.one = 1
ld.two = 2
ld.three = None
ld.five = 5
ld.six = None

def ne2ld(ne, ld):
   ne_dict = ne.__dict__
   print 'ne_dict:', str(ne_dict)

   for key, value in ne_dict.iteritems():
      if not getattr(ld, key, None):
         setattr(ld, key, value)

   print ld.__dict__

